The invention relates to a method for producing tooth parts from dental-grade metal powder. Within the context of the present invention, tooth parts are understood particularly as bridge structures and caps, along with full prostheses.
Prior Art
In the dental industry, the lost-wax casting process continues to be the most commonly used process for producing tooth parts from metal, in which process a wax mold is modeled on a working model, with the shape of said mold corresponding to the object to be cast. Using this wax mold, a cavity is formed in a casting mold, which is then cast with metal. This method is highly costly and requires a great deal of artisanal skill.
For this reason, a number of methods have already been proposed, which are implemented using not molten metal but metal powder which is sintered. None of these methods has gained acceptance in practical use for a wide variety of reasons.
However, one promising method is disclosed in EP 1 885 278 B1 (Wolz). In this case, a metal layer is deposited by electrophoresis from a suspension fluid onto a model, wherein the deposited metal layer is stabilized by sintering, in that it is either fixed on a firing support, or in that it remains on a plated stump, or is placed in a muffle filled with embedding compound or temperature-resistant powder.
In addition to the production of tooth parts from metal, the production of fully ceramic dental prostheses is known, and makes up approximately 10% of the dental market. One customary method consists in using CAD/CAM techniques to mill a framework out of an isostatically pre-pressed block of ceramic, particularly zirconium oxide. In this case, the patient's teeth or a working model is/are scanned, and the framework is milled on the basis of the scanned model. With this method, tooth parts are also milled from solid metal blocks. One major disadvantage of this method is that the milling of ceramic produces dust, and also places high mechanical demands on the milling machine. As a result, the service life of simple, in other words inexpensive, milling machines is too short. Even more complex milling machines, the investment costs of which frequently exceed the economic capability of an average dental laboratory, require an unjustifiable expenditure on maintenance. For these reasons, many dental laboratories no longer even use milling machines.